The present invention relates to integrated circuits in general and, in particular, to optimized delay cells for voltage-controlled oscillators.
A voltage-controlled oscillator (VCO) is a key component in a typical phase-lock loop, or PLL. Along with a phase-frequency detector, a charge pump, and a loop filter, a VCO is capable of generating a clock whose frequency and phase have a well-defined (deterministic) relationship to the frequency and phase of a reference clock. As a set, they form the PLL. PLLs are used in various applications such as clock synthesis, clock distribution, signal de-skewing, and as filters in reducing jitter within other applications. VCOs therefore, are a commonly occurring circuit element in clock circuitry.